Standard: These are the most common domino and simply fall when pushed over, knocking over adjacent dominoes or falling off the ledge. If two dominoes on opposite sides of a small gap both attempt to fall through at the same time, they will become lodged together, forming a "bridge" across the gap, although G.I. cannot use them to walk over the gap.
Stopper: These dominoes refuse to be toppled, rebounding any other dominoes that fall against them. They can however be picked up and carried by G.I. These are the only dominoes in the game that do not need to be pushed over in order for the level to be completed.
Delay: These act in exactly the same way as a Standard domino, but remain standing for a short while before falling over. In this short period they act as if they were a Stopper, with other dominoes bouncing off them.
Ascender: These blocks defy gravity, and will float upwards when hit by another block. They continue to rise until they meet the underside of a ledge, at which point they lie flat against the ceiling in the direction they were hit. If G.I. walks off a ledge holding an ascender domino, it floats up to the ceiling and then needs to be pushed by another domino in order to complete the level. Ascender dominoes can be discarded before the push if they are not needed by walking off a ledge with them and letting them float off the screen.
Bridger: Bridger blocks act in the same way as a Standard block, however when a bridger falls off the edge of a ledge where the gap is only one "space" wide (where you would be able to fit one domino), it will extend the ledges and bridge the gap.
Exploder: Essentially the opposite of Bridger dominoes, when hit this domino will explode, creating a gap in the ledge one "space" wide. The explosion does not damage other dominoes or G.I., however it can damage ladders and make them impossible to climb. The resulting gap in the ledge may also make it impossible for G.I. to reach the exit, forcing the player to restart the level.
Vanisher: Vanisher dominoes disappear as soon as they land. This is often useful in situations where the domino "run" needs to lead past the level's exit. The vanisher leaves a gap in the line of toppled dominoes, allowing G.I. to access the exit.
Splitter: The Splitter domino divides into two separate dominoes when it is hit. If a Splitter is located in a line of toppling dominoes, when it is hit, one half will continue the chain whilst the other half will fall backwards, creating rubble and thus failing the level. To use Splitters properly requires the dropping of any style of domino from directly above, causing it to divide and start two new domino chains. A Splitter domino's best use is as an effective "free push". Whilst G.I. may only push once per level, chains may still be started off by walking off a ledge whilst carrying a domino, causing the domino to fall onto a Splitter placed below.
Tumbler: Tumbler dominoes act in the same way as a Standard domino, however when a Tumbler domino lands on the floor, it flips up again and falls, effectively rolling along the ledge. This allows a chain of dominoes to continue across gaps where there are no dominoes.
Trigger: In a sense the most important domino, the Trigger domino must always be the final domino to fall, and must always fall exactly flat (i.e. it must not land on top of another fallen domino). This causes the exit to open to allow G.I. through. Occasional levels in the game have multiple Trigger dominoes, which must fall at (roughly) the same time.